1. Field of the Invention
The present invention relates to a three-dimensional image display device for displaying three-dimensional image data and a three-dimensional image recording device for capturing, recording, and regenerating a three-dimensional object for display.
2. Description of the Related Art
Recently, a variety of image displaying technologies have enabled an object to be displayed in three dimensions. For example, two images to be captured separately by a left eye and a right eye are given to respective eyes to regenerate the three-dimensional image of an object. The effect of the three-dimensional image is based on the difference in vision between the left and right eyes, and can be obtained both with and without glasses. Methods using glasses are: the wave-length separating method in which left and right images are separated through the difference in wave length of light, that is, red and blue color glasses are used; the polarization separating method in which images are separated by polarization glasses for separating images based on the difference in light polarization state; and the time divisional separating method in which left and right images are separated through glasses while being alternately displayed in time-division manner. These methods are applied to movies, TV, video, and other display devices.
Methods without glasses are: the parallax barrier method in which images corresponding to left and right eyes are alternately and divisionally displayed on a display screen as long and narrow strips with a vertical static slit barrier positioned before the screen; and the lenticular method in which long semi-cylindrical lenses are arranged horizontally from left to right and a divisional display screen is provided at the position of the lens focus to display images corresponding to left and right eyes.
Other methods than those depending on the difference in vision are technologies of generating a spatial image and displaying it in three dimensions. For example, a technology of recording and regenerating a three-dimensional image using a hologram, a technology of integral photography using fly's eyes lens in which a number of small convex lenses are spread all over a plane; or a pin hole panel in which a number of pin holes are used instead of convex lenses.
A three-dimensional image is demanded in various industrial fields such as designing three-dimensional structures, three-dimensional molecular structures, technical trainings with three-dimensional pictures and images, etc. in addition to the demand as amusement media such as TV, movies, video, etc.. Now demanded is a three-dimensional image which not only appears as an illusion as if it were a three-dimensional image but also can be realized as a true three-dimensional object by being observed from various directions, and as colored and dynamic image.
The above described a three-dimensional image displaying technologies have respective problems as follows.
(1) In the method of displaying a three-dimensional image based on the difference in vision between left and right eyes, the displayed image is not really a three-dimensional image, but simply appears as if it were a three-dimensional image. Therefore, the image cannot appear in three dimensions from all directions by being viewed from above or below, or from its left or right side as can a hologram. That is, the positional correlation between a viewer and the screen is limited to a specified narrow scope (lenticular method and parallax barrier method), or a good three-dimensional image requires that the line connecting the left and the right eyes should be parallel with the horizontal direction of the screen in the polarization filter method). Therefore, the viewer cannot see the image in a natural posture. Additionally, since the viewer must wear immediately before his or her eyes the glasses of filters (red-and-blue filters, polarization filter, time-division filters, etc.) to separate the images for respective eyes, they are actually annoying to the viewer. These glass-type filters are not required by the lenticular method which uses a special lens plate immediately before a screen or the parallax barrier method which uses a barrier with slits. PA1 (2) In the three-dimensional image displaying method using holograms, an image is calculated, constructed, and recorded by a computer as optical interference fringes. It is a very complicated procedure and takes an unpractically long processing time. Furthermore, it is very difficult to display dynamic images requiring much more image data than static images. The optical interference further complicates a displaying of colored images. PA1 (3) In the integral photographic method, the precision of lenses must be identically maintained between recording and regenerating times in dimension, installation, and position relative to a facing screen. Thus, it is technically difficult to use this method successfully. Furthermore, since the focal depth is small, also small is the depth of an image clearly regenerated from a photographically recorded image. Additionally, this method does not assure the perfect reproductivity of images because the directions of the rays emitted from respective parts of an object can be recorded only partially.